What We Know About Philadelphia Gunman Nicholas Glenn

Nicholas Glenn shot at his victims relentlessly, not speaking a single word as he emptied the rounds.

America witnessed yet another murderous rampage when 25-year-old Nicholas Glenn, a gun in hand and blinded by hate, went on a shooting spree in Philadelphia.

Although his prime target were police officers, he also killed a bystander in his rage.

Like most shooting sprees, this was too fueled by hate.

However, Glenn had a very specific hatred toward the police, as he detailed in the note he left behind titled "Doom." In the letter, he talked of his resentment toward one police officer in particular, and the entire force in general, according to Philadelphia Police Commissioner Richard Ross.

A few blocks from the University of Pennsylvania campus, 46-year-old Sgt. Sylvia Young was sitting in her patrol car when Glenn approached her vehicle, and without a word, started shooting relentlessly.

He shot at her 15 times.

Young was extremely lucky; her bullet-proof vest shielded her organs from fatal damage. She is expected to survive.

Glenn then shot aimlessly, his bullets tearing through the air. At a nearby bar, he targeted the security guard. Inside, he emptied five more rounds. He robbed a woman and then shot her in the leg.

He went outside and shot approximately 14 times at a man and woman sitting in the car. The man is wounded, but the woman was pronounced dead at Penn Presbyterian Hospital.

Glenn was eventually cornered in an alley by University of Pennsylvania police officer Ed Miller, a retired police officer who had responded to a call for assistance. Glenn was fatally shot. Miller was also shot, but remains in stable condition.

Glenn was a foster child whose path to accused murderer was filled with several run-ins with the law, according to court records.

In fact, his criminal history dated back to 2009 when he was arrested for alleged involvement in gang rape. The case was later withdrawn by prosecutors for unknown reasons. He was also arrested on suspicion of a number of drug-related charges.

In 2015, he spent about seven months in prison for a probation violation.

Joan Griffin, who took Nicholas Glenn into her West Philadelphia home more than a decade ago along with his brother and sister, believes Glenn's time in prison somehow changed him.

"I guess he snapped in prison. When he got locked up, he didn't come out the same," she said, noting that he had became aloof, disengaged and "acting like he didn't know anybody.”

Glenn's shooting spree left one dead, in addition to his own death. All of the other five victims are said to be in stable condition.